The invention relates to a precision positioning unit and further to a linear movement control unit favorably employable for the precision positioning unit.
The precision positioning unit is generally employed in mechanical industry and electronic industry to manipulate an article such as a workpiece in relationship to working tools A typical known positioning unit illustrated in FIG. 7 of the attached drawings.
In FIG. 7, the positioning unit is composed of a table 71 an which an article is placed, a support member 73, a screw rod 74, and a rod actuator 75 which is connected to an electric source (not shown) and causes rotation of the screw rod 74. When the screw rod 74 rotates, the support member 73 and the table 71 in combination move forward or backward. When the table 71 reaches a predetermined position, the electric connection to the rod actuator 75 is cut, accordingly the rotation of the screw rod 74 ceases to stop the linear movement of the table.
The positioning unit of FIG. 7 can not satisfactorily function for precise positioning, because a series of the necessary operations, namely, the cut of electric connection, cease of operation of the rod actuator 75, cease of rotation of the screw rod 74, and cease of the movement of the combination of the support member 73 and the table 81 by way of friction, require a considerable time. Therefore, it is not easy to position the table at the predetermined side very precisely, so long as the known positioning unit is employed. The known positioning unit also has another problem in that the screw surface of the screw rod 74 gradually wears in the course of its operation, and the worn screw surface is not appropriate for the precise positioning of the table 71.
It is an object of the invention to provide an improved precise positioning unit.
It is another object of the invention to provide a precise positioning unit whose precise positioning reliability is maintained for a long period of time, even after it is repeatedly operated.
It is a further object of the invention to provide a linear movement control unit which is employable for different uses such as control of a diaphragm valve installed in a fluid control system.
The present invention resides in a precision positioning unit comprising a table on which an article is to be placed, a linearly movable rod which is connected with the table at one end or a vicinity thereof and further connected with a rod actuating device at another end or a vicinity thereof, said rod actuating device capable of linearly moving the rod forward and backward, characterized in that:
the rod is connected with the rod actuating device via cushion mechanism; and
by the side of the rod is placed a rod movement control device comprising an elastic member, a ultrasonic transducer, and a ultrasonic emitting surface, the elastic member being constituted to push the ultrasonic emitting surface to a side surface of the rod when the ultrasonic transducer is inactive, and the ultrasonic transducer functioning to draw the ultrasonic emitting surface away from the rod when it is active.
The invention also resides in a linear movement control unit comprising a linearly movable rod which is connected with a rod actuating device at one end or a vicinity thereof, said rod actuating device capable of linearly moving the rod forward and backward, characterized in that:
the rod is connected with the rod actuating device via cushion mechanism; and
by the side of the rod is placed a rod movement control device comprising elastic member, a ultrasonic transducer, and a ultrasonic emitting surface, the elastic member being constituted to push the ultrasonic emitting surface to a side surface of the rod when the ultrasonic transducer is inactive, and the ultrasonic transducer functioning to draw the ultrasonic emitting surface away from the rod when it is active.